Stainless steel flanges are not completely rust-free, but their oxidation resistance is stronger than ordinary steel, so it is called stainless steel.
Stainless steel not only can resist atmospheric oxidation but also can corrode in a medium containing acid, alkali, and salt. However, the size of its corrosion resistance varies with the chemical composition of the steel itself, the interaction state, the use conditions, and the type of environmental media. Such as 304 flanges, in a dry and clean atmosphere, there is very good corrosion resistance, but it will be moved to coastal areas, in the sea containing a lot of salt fog, it will rust quickly, 316 flange performs well. Therefore, it is not any kind of stainless steel, which is resistant to corrosion and rust in any environment.